CeCl3·H2O/NaI-Promoted stereoselective synthesis of 2,4-disubstituted chiral tetrahydroquinolines

d-Glycals readily undergo cyclization with aryl amines in the presence of CeCl₃·7H₂O-NaI under mild and neutral conditions to afford a novel sugar derived tetrahydroquinoline derivatives in good yields with high stereoselectivity. The stereochemistry of the products was assigned by using various NMR studies.     

CeCl3·7H2O/AcCl-catalyzed Prins-Ritter reaction sequence: a novel synthesis of 4-amido tetrahydropyran derivatives

Homoallylic alcohols, carbonyl compounds and nitriles undergo a smooth tandem Prins-Ritter type cyclization in the presence of CeCl₃·7H₂O/AcCl at ambient temperature to produce 4-amido tetrahydropyrans in high yields with all cis-selectivity. Spirocyclic 4-amido tetrahydropyrans are obtained in the case of cyclic ketones.     

Glycerin and CeCl3·7H2O: a new and efficient recyclable medium for the synthesis of bis(indolyl)methanes

Glycerin and CeCl₃·7H₂O were successfully used in recyclable catalytic system for the synthesis of several bis(indolyl)methanes in good to excellent yields through the reaction of indoles with aldehydes. The method is applicable to aliphatic and aromatic aldehydes, and the mixture of glycerin and CeCl₃·7H₂O can be reused up to five times without special treatment and with comparable yields.     

CeCl3·7H2O: an efficient and reusable catalyst for the preparation of β-acetamido carbonyl compounds by multi-component reactions (MCRs)

A convenient method for the preparation of β-acetamido carbonyl compounds is described by multi-component reactions of aromatic aldehydes, enolizable ketones or β-keto esters and acetonitrile in the presence of acetyl chloride and 10 mol % CeCl₃·7H₂O at room temperature.     

Catalytic oxidation of thiols to disulfides using iodine and CeCl3·7H2O in graphite

A very simple procedure for the efficient oxidation of thiols to disulfides catalyzed by I₂/CeCl₃·7H₂O in graphite and ethyl acetate as the solvent, in an open system at room temperature is described. The reaction proceeds cleanly under mild conditions and was performed with aromatic, aliphatic, and heterocyclic thiols.     

Imidazo[1,5-a]pyridine-3-ylidenes—pyridine derived N-heterocyclic carbene ligands

The ready synthesis of differently substituted 2H-imidazo[1,5-a]pyridin-4-ium bromides is reported. These salts are precursors for a new class of N-heterocyclic carbene ligands. As a consequence of their bicyclic geometry, these ligands are capable of influencing the coordination sphere of a carbene bound metal. The usefulness of these ligands was demonstrated in the palladium-catalyzed Suzuki-Miyaura cross-coupling of sterically hindered aryl chlorides.     

A highly efficient synthesis of imidazo-fused polyheterocycles via Groebke–Blackburn–Bienaymè reaction catalyzed by LaCl3·7H2O

A highly efficient and mild protocol for the synthesis of imidazo-fused polyheterocycles via Groebke–Blackburn–Bienaymè reaction under the influence of catalytic amount of lanthanum chloride heptahydrate has been described. A wide range of nitrogen-enriched polyheterocycles are synthesized with high yields under neat conditions.     

Parallel iterative solution-phase synthesis of 5-amino-1-aryl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylic acid amide derivatives

The parallel iterative solution-phase synthesis of 5-amino-1-aryl-[1,2,4]triazolo[1,5-a]pyridine-7-carboxylic acid amide derivatives is described. The key intermediate 2,6-bis-aminopyridine-4-carboxylic acid methyl ester was synthesised in a two step procedure in 64% overall yield and elaborated to a variety of triazolopyridine-5-carboxylic acid methyl ester by selective pyridine-N-amination, condensation of the adduct with a wide selection of aldehydes and subsequent cyclisation and oxidation. The desired esters were obtained in yields up to 70%. The final transformation to the amide derivatives was accomplished by application of carefully optimised reaction conditions thus giving access to a library of total 500 triazolopyridine amide derivatives. Iterative synthetic cycles (12-48 library members each) allowing for maximal flexibility in chemistry and maximal efficiency in in vitro biological activity optimisation guided by molecular modelling efforts constitute a synergistic procedure for rapid lead optimisation.     

ZrOCl2·8H2O: an efficient Lewis acid catalyst for the one-pot multicomponent synthesis of β-acetamido ketones

Aromatic aldehydes were reacted in one-pot with enolisable ketones, acetonitrile and acetyl chloride at ambient temperature in the presence of ZrOCl₂·8H₂O to furnish the corresponding β-acetamido ketones in very good to excellent yields. X-ray crystallographic analysis of one anti-β-acetamido ketone exhibited a two-dimensional supramolecular framework by a combination of N-H?O, C-H?O and C-H?π (arene) hydrogen bonds.     

The first example of the C-3 alkylation of indoles with cyclopropyl ketones promoted by CeCl3·7H2O/LiI

Indoles undergo smooth alkylation with cyclopropyl ketones in the presence of the CeCl₃·7H₂O/LiI reagent system in refluxing acetonitrile under neutral conditions to produce the corresponding C-3 substituted indole derivatives in good to high yields and with high selectivity. The use of CeCl₃·7H₂O/LiI makes this method simple, convenient, and cost-effective.     

Regioselective synthesis of 1- and 4-substituted 7-oxopyrazolo[1,5-a]pyrimidine-3-carboxamides

The synthesis of 7-substituted pyrazolo[1,5-a]pyrimidine-3-carboxamides was studied. First, methyl 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylate (5) was prepared in three steps from methyl 5-amino-1H-pyrazole-4-carboxylate (3). Treatment of 5 with POCl₃ gave the highly reactive 7-chloro derivative 10, which was reacted with amines, benzyl alcohol, and phenylboronic acid in the presence of Pd-catalyst to give the corresponding 7-substituted derivatives 11. Hydrolysis of the esters 5 and 11 followed by amidation gave the corresponding carboxamides 16a–h and 15. Regioselectivity of N-alkylation of 7-hydroxypyrazolo[1,5-a]pyrimidine-3-carboxylic acid derivatives 5 and 16 was tunable by the carboxy function. Alkylation of the secondary amides 16a–f furnished the 1-alkyl derivatives 17a–f, whereas the ester 5 and the tertiary amides 16g,h gave the 4-alkyl derivatives 14a–d and 16m,n, selectively.     

Microwave-assisted organic synthesis of 3-substituted-imidazo[1,5-a]pyridines

3-Substituted-imidazo[1,5-a]pyridines were conveniently synthesized in two steps from commercially available picolinic esters under microwave irradiation conditions.     

Nonisothermal Kinetics of Dehydration Process of [Sm（m-CIBA）3phen]2·2H2O and [Sm（p-CIBA）3phen]2·2H2O

Compounds [Sm（m-CIBA）3phen]2.2H20 and [Sm（p-CIBA）3phen]2·2H20（m-CIBA=m-chlorobenzoate, pClBA=p-chlorobenzoate, phen=l,10-phenanthroline） were prepared. The dehydration processes and kinetics of these compounds were studied from the analysis of the DSC curves using a method of processing the data of thermal analysis kinetics. The Arrhenius equation for the dehydration process can be expressed as lnk=-38.65-243.90×l0^3/RT for [Sm（m-CIBA）3phen]2·2H2O, and lnk=38.70-172.22×103/RT for [Sm（p-CIBA）3phen]2·2H2O. The values of △H^1, △G^1, and △S^1 of dehydration reaction for the title comnonnds are determined respectively.     

An efficient synthesis of 3-amino-2-arylimidazo[1,2-a]pyridines

An efficient synthesis of 3-amino-2-arylimidazo[1,2-a]pyridines is described via a novel multicomponent reaction between 2-aminopyridines, benzaldehydes and imidazoline-2,4,5-trione under solvent-free conditions.     

The CeCl3·7H2O-NaI system as promoter in the synthesis of functionalized trisubstituted alkenes via Knoevenagel condensation

The arylidene malonates with two different geminal carboxylate functions, a suitable class of substrates of several synthetic and pharmacological studies, are easily available through Knoevenagel condensation of ethyl tert-butyl malonate and different aromatic aldehydes. The results have increased the potentialities of CeCl₃·7H₂O-NaI system as a type of water-tolerant green Lewis acid promoter for carbon-carbon bond forming procedures.     

Hydrothermal synthesis of WO3·1/3H2O nanorods and study of their electrical properties

Crystalline tungsten oxide hydrate (WO₃·1/3H₂O) nanorods have been prepared by a hydrothermal process using Na₂WO₄·2H₂O and 4-phenylbutylamine as a structure-directing agent. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and thermal analysis techniques have been used to characterize the structure, morphology and composition of the nanorods. The WO₃·1/3H₂O nanorods are up to several hundred nanometers in length, and the widths and thicknesses are 40 and 8 nm, respectively. A study of the electric properties in the temperature range 170–730 °C and frequency range 5–13 MHz is reported. The obtained results show that the activation energies are about 0.07, 0.63 and 2.46 eV for o-WO₃·1/3H₂O, h-WO₃ and m-WO₃, respectively. The as-synthesized materials are promising for chemical and energy-related applications such as catalysts and electrochemical devices, and may be applied in rechargeable lithium-ion batteries.     

Nd(Gly)2Cl3·3H2O和Pr(Ala)3Cl3·3H2O的热力学性质

利用精密自动绝热热量计测定了Nd(Gly)₂Cl₃·3H₂O在80-357K和Pr(Ala)₃Cl₃·3H₂O在80-374K温区的热容. 根据两个化合物的热容计算出了相对于参考温度298.15K的热力学函数(H_T?H_298.15)和(S_T?S_298.15). 根据热重(TG)分析结果, 提出了这两个稀土化合物可能的热分解机理. 利用溶解-反应恒温热量计测定相关化合物的溶解焓并设计盖斯热化学循环, 计算出了两个化合物的标准摩尔生成焓.     

Formation of [CoCl4(H2O)2] complex in CoCl2·MgCl2·8H2O double salt: structural and energetic properties of [MCl4(H2O)2] and [M(H2O)6] (M=Mg, Co)

The crystal structure of the double salt CoCl₂·MgCl₂·8H₂O has been determined by the X-ray diffraction method. It crystallizes in the space group with a=6.0976(9), b=6.308(1), c=8.579(3) Å, α=81.99(2)°, β=88.40°, γ=84.61(1)°, Z=1, and R=0.027. The crystal consists of two kinds of well separated octahedra, [CoCl₄(H₂O)₂]²⁻ and [Mg(H₂O)₆]²⁺. The former is unique as aquachloro complexes of Co²⁺. In order to elucidate the reason prepared as such unique complexes in the double salts, formation energies for [MCl₄(H₂O)₂]²⁻ and [M(H₂O)₆]²⁺ (M=Co, Mg) have been calculated by using the density functional methods, and it has been revealed that the formation energies of the first coordination sphere for the metal ions and the Cl⁻?H₂O hydrogen bond networks around [CoCl₄(H₂O)₂]²⁻ play a decisive role in forming [CoCl₄(H₂O)₂]²⁻ with the regular octahedral geometry in the double salt.     

First synthesis of 7-amido-[1,2,4]triazolo[1,5-a]pyrimidines using halogen-metal exchange

A new and efficient methodology for the preparation of novel 7-carboxyl-triazolopyrimidine derivatives via the halogen-metal exchange is described. In addition, we showed that this new method can be useful for the synthesis of amides, esters, and ketones by using different carbamoyl chlorides, isocyanides or acyl chlorides as electrophile.     

An efficient and one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by InCl3·3H2O

InCl₃·3H₂O was found to be a mild and effective catalyst for the efficient, one-pot, three component synthesis of 2,4,5-trisubstituted imidazoles at room temperature. Moreover, the utility of this protocol was further explored conveniently for the one-pot, four component synthesis of 1,2,4,5-tetrasubstituted imidazoles in high yields.